A quick search reveals that at least in 1903, all passport applicants took an oath of allegiance:
http://books.google.com/books?id=r3I3AAAAMAAJ&pg=PA80&lpg=PA80&dq=passport+oath+of+allegiance+1900s&source=bl&ots=O05bQCfBKv&sig=PIY1zhkPOEWJQsGPaKgd7302zSU&hl=en&ei=p2zXS5iHBJHwsQOzqOGrBg&sa=X&oi=book_result&ct=result&resnum=9&ved=0CDQQ6AEwCA#v=onepage&q&f=false
You are welcome.
I rebutted it in the post above.